Motor dysfunction is associated with schizophrenia, and recent longitudinal studies indicate
that it precedes the onset of clinical symptoms. Of particular interest is the heightened occurrence
of involuntary movements, which are apparent as early as infancy and suggest the presence of
subcortical brain abnormalities. In this article, we present the results of a study of spontaneous
movements in adolescents with schizotypal personality disorder (SPD). SPD is a syndrome that
has been shown to be genetically linked with schizophrenia and is often observed prior to the
early adult onset of schizophrenia. Systematic coding of videotapes of diagnostic interviews
revealed that the SPD group showed significantly more involuntary movements of the head,
trunk, and upper limbs than did normals and adolescents with other personality disorders. There
were no diagnostic group differences in the rate of voluntary movements. Salivary cortisol,
measured before the interview, was positively correlated with involuntary movements. Taken
together, the findings provide further support for the hypothesized etiologic relation between
SPD and schizophrenia. Based on a neural diathesis-stress model, potential underlying
mechanisms are discussed.